In the early 1900's, James L. Kraft patented a method of making process cheese which had distinct technical advantages over natural cheese. Namely, process cheese has an extended shelf-life in comparison to natural cheese, is resistant to separation when cooked, and can be formed into a wide variety of product forms (e.g., slices, loaves, sauces, dips, and the like). Process cheese is produced by comminuting and mixing together natural cheese, other dairy ingredients, emulsifiers, salt, and optionally food colorings. Various types of natural cheese as well as blends thereof may be used to provide consumer preferred flavor profiles. Pasteurized process cheese is heated to at least 150° F. for at least 30 seconds.
Despite the technical advantages over natural cheese, it would be desirable to provide process cheeses having improved attributes which would appeal to larger numbers of consumers. For example, some consumers may perceive the emulsifying salts as “chemicals” and prefer products containing more natural ingredients. Emulsifying salts also tend to modify the desired flavor of the natural cheeses by providing a milder and saltier flavor profile; some consumers may prefer a more natural and intense cheese flavor profile in a process cheese. In addition, processed cheese generally contains higher levels of sodium than natural cheese since processed cheese contains sodium based emulsifying salts as well as sodium chloride.
Process cheese is prepared by blending cheese, emulsifying salts, and other ingredients under conditions of heat and shear. Emulsifying salts are useful for creating a cheese that melts smoothly when cooked, as opposed to separating into different phases. The most common emulsifying salts are sodium and potassium citrates, monophosphates, and polyphosphates. Emulsifying salts complex with calcium ions in the cheese to solubilize the protein, increase protein hydration and swelling, to facilitate emulsification of fat, and to adjust and stabilize pH. Emulsifying salts reduce the tendency for fat globules in the cheese to coalesce and pool on the surface of the molten cheese. Emulsifying salts allow a cheesemaker to pasteurize the cheese product without deterioration of the cheese texture.
Prior attempts to produce a process cheese without emulsifying salts have generally been problematic. For example, European Patent Application 0016292 provides a process for preparing process cheese wherein ion exchange is effected using an ion exchange column; this approach is extremely cumbersome in manufacturing practice and would be extremely costly in terms of capital equipment and operating costs. “Pasteurized blended cheese” (as defined in 21 C.F.R. 133.167) identifies a good tasting smooth pasteurized cheese product without emulsifying salts. Manufacturers do not, however, generally offer such “pasteurized blended cheese” products because of high cost (i.e., generally requires over 90% natural cheese) and its lack of manufacturing robustness (i.e., the emulsion easily separates or breaks at temperatures above 157° F., making it difficult to pasteurize on a consistent basis). European Patent Application 0535728 also provides a method of heating an unpasteurized cheese blend comprising 30 to 90 percent unripened cheese and a protein source to 35 to 65° C. (i.e., approximately 95 to 149° F.). Since the heating step is carried out below pasteurization temperatures, the resulting cheese is not pasteurized.
Thus, although process cheese has a number of beneficial qualities there is a desire to produce a cheese product that maintains beneficial qualities including extended shelf-life and resistance to separation during heating, but without the addition of certain additives, such as emulsifying salts. There is an additional desire to decrease the amount of added sodium in process cheese and further, to improve the quality of the natural cheese flavor in the product at a modest cost.